We reviewed data on 171 patients with refractory headache treated by continuous intravenous dihydroergotamine mesylate (i.v. DHE 45) and repetitive i.v. DHE and compared the efficacy of continuous i.v. DHE to repetitive i.v. DHE. One hundred (58.5%) patients had refractory chronic daily headache. Seventy-one (42%) had drug rebound headache. One hundred thirty-eight (81%) had refractory migraine without aura, and 28 (16%) had migraine with aura. Treatment consisted of either continuous i.v. DHE by infusion pump or repetitive i.v. DHE and withdrawal of excessively used analgesics, analgesic narcotics, ergotamines, or benzodiazepines. Eighty-nine (92.5%) patients treated with continuous i.v. DHE became headache-free; the majority, 62 (64.5%), within 3 days. Sixty-five (86.5%) patients treated by repetitive i.v. DHE became headache-free, 50 (66.5%) within three days. The average hospital stay for both treatment groups was 4 days. Twelve (12.5%) of the continuous group and 12 (16%) of the repetitive group were headache-free within 24 hours. The average length of time to become headache-free was similar for the two groups, 3.06 days for continuous i.v. DHE and 2.94 days for repetitive i.v. DHE. The most common side effect was nausea, followed by diarrhea, vomiting, and leg cramps. We conclude that DHE can be accurately and easily administered by continuous i.v. infusion pump, and that continuous i.v. DHE is a safe and efficacious mode of treatment producing results similar to repetitive i.v. DHE.